xfs: move some code around inside xfs_bmap_shift_extents

For the first right move we need to look up next_fsb.  That means
our last fsb that contains next_fsb must also be the current extent,
so take advantage of that by moving the code around a bit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 99b5fa5c4b8d420101ec452b551c32bd0e7239be..e529bed6be412fc68779b992aa7d690e1c45b8d7 100644 (file)
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -6127,7 +6127,6 @@ xfs_bmap_shift_extents(
        ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
        ASSERT(direction == SHIFT_LEFT || direction == SHIFT_RIGHT);
-       ASSERT(*next_fsb != NULLFSBLOCK || direction == SHIFT_RIGHT);
 
        ifp = XFS_IFORK_PTR(ip, whichfork);
        if (!(ifp->if_flags & XFS_IFEXTENTS)) {
@@ -6159,43 +6158,48 @@ xfs_bmap_shift_extents(
         * In case of first right shift, we need to initialize next_fsb
         */
        if (*next_fsb == NULLFSBLOCK) {
-               gotp = xfs_iext_get_ext(ifp, total_extents - 1);
+               ASSERT(direction == SHIFT_RIGHT);
+
+               current_ext = total_extents - 1;
+               gotp = xfs_iext_get_ext(ifp, current_ext);
                xfs_bmbt_get_all(gotp, &got);
                *next_fsb = got.br_startoff;
                if (stop_fsb > *next_fsb) {
                        *done = 1;
                        goto del_cursor;
                }
+       } else {
+               /*
+                * Look up the extent index for the fsb where we start shifting. We can
+                * henceforth iterate with current_ext as extent list changes are locked
+                * out via ilock.
+                *
+                * gotp can be null in 2 cases: 1) if there are no extents or 2)
+                * *next_fsb lies in a hole beyond which there are no extents. Either
+                * way, we are done.
+                */
+               gotp = xfs_iext_bno_to_ext(ifp, *next_fsb, &current_ext);
+               if (!gotp) {
+                       *done = 1;
+                       goto del_cursor;
+               }
        }
 
        /* Lookup the extent index at which we have to stop */
        if (direction == SHIFT_RIGHT) {
-               gotp = xfs_iext_bno_to_ext(ifp, stop_fsb, &stop_extent);
+               xfs_iext_bno_to_ext(ifp, stop_fsb, &stop_extent);
                /* Make stop_extent exclusive of shift range */
                stop_extent--;
-       } else
+               if (current_ext <= stop_extent) {
+                       error = -EIO;
+                       goto del_cursor;
+               }
+       } else {
                stop_extent = total_extents;
-
-       /*
-        * Look up the extent index for the fsb where we start shifting. We can
-        * henceforth iterate with current_ext as extent list changes are locked
-        * out via ilock.
-        *
-        * gotp can be null in 2 cases: 1) if there are no extents or 2)
-        * *next_fsb lies in a hole beyond which there are no extents. Either
-        * way, we are done.
-        */
-       gotp = xfs_iext_bno_to_ext(ifp, *next_fsb, &current_ext);
-       if (!gotp) {
-               *done = 1;
-               goto del_cursor;
-       }
-
-       /* some sanity checking before we finally start shifting extents */
-       if ((direction == SHIFT_LEFT && current_ext >= stop_extent) ||
-            (direction == SHIFT_RIGHT && current_ext <= stop_extent)) {
-               error = -EIO;
-               goto del_cursor;
+               if (current_ext >= stop_extent) {
+                       error = -EIO;
+                       goto del_cursor;
+               }
        }
 
        while (nexts++ < num_exts) {